Seal Online is a Massively Multiplayer Online Role-Playing game, developed by the Korean company - YNK Partners Inc. As of 7 February 2008, official versions of the game are available in South Korea, Japan, Taiwan, Thailand, Indonesia, and the United States.

The English version of Seal Online was expected to be released in Q3 of Year 2005 when Grigon Entertainment announced that there would be an English version of Seal Online.An English website was made by them. However within 2 months, the site closed down and there were no more news of an English translated version of the game.

After two years, a website was created for Seal Online. It had a post announcing the arrival of Seal Online in English to the United States. The English Seal Online was finally released on the 19 November 2007 at 8pm EST by YNK Interactive.

Seal Online is mostly a point-and-click MMORPG; movement, combat, and many other commands are all controlled by mouse. The player can choose from 7 different classes to start with. However, if the player chooses to start with the Beginner, he/she can choose to job change into the other 6 classes when he reaches Level 10.

Seal Online's travel system uses a method called 'Warp Gates'. These gates, located in various towns, allow the player to move to other maps. Players may use scrolls, set revive points, use the Wagon Driver NPC, or just type out a Teleport command for a small fee to warp to different maps.

The player can learn skills to trade, open or join a guild after completing a quest, open a chat room, create a party to fight monsters more effectively, open an in-game bank account to hold or collect more items and money, nurture a pet, do quests, and fish.

Seal Online's level up system uses a point method. Skills level up with skill points. Each time a player levels up, they receive a set number of skill points and status points, which they then may use to strengthen their character.